1. Field of the Invention
This invention relates to a buckstay system for vapor generators and the like, and more particularly, to an adjustable buckstay system for controlling vibrations in an operating vapor generator.
2. Description of the Prior Art
Conventional vapor generators comprise a furnace section defined by a plurality of walls formed of vertically disposed, adjacent tubes through which a fluid such as water is passed in order to absorb heat from the surface. These tubes are relatively long and thin walled and may be supported from above to accommodate vertical expansion.
It is also known to provide a system of buckstays to protect the furnace walls against the effects of excessive lateral deflections which may result from relative pressure differentials inside and outside of the furnace walls. Such buckstay systems may comprise beams such as I beams, for example, extending horizontally adjacent the exterior tube surfaces at various elevations of the furnace walls and connected to the walls by suitable lugs, and tension ties arranged parallel to the beams and between the beams and walls. Adjacent beam ends are connected to one another through corner link assemblies which are also connected to the tension ties. The entire system is assembled in a manner to permit relatively free differential thermal expansion between the hot furnace walls and the cooler buckstay beams by means of clearances between the buckstay beams and the furnace walls, between the walls and the tension ties and within the corner link assemblies.
In view of the described organization of the structure, it will be appreciated that the tubes are quite flexible and tend to vibrate under the influence of pressure pulsations propagated through the gas in the furnace section when the unit is fired.
Those skilled in the art will appreciate that the destructive effects of vibration can lead to failure of affected elements such as buckstay system components, for example, and that the aforementioned clearances represent an important factor influencing the vibratory responses within the overall generator system since these clearances render the behavior of the structure nonlinear and highly unpredictable. Thus, the reduction or elimination of vibration is a desired objective in the vapor generator art.